tests for constructor tear-offs (dart-archive/linter#2901)

Author: pq

test_data/rules/experiments/constructor_tearoffs/rules/unnecessary_statements.dart

@@ -0,0 +1,191 @@
+// Copyright (c) 2021, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// test w/ `dart test -N unnecessary_statements`
+
+void constructorTearOffs() {
+  MyClass.new; // LINT
+  MyClass.named; // LINT
+
+  var m = MyClass.new;
+  m().foo; // LINT
+  m().field; // LINT
+}
+
+String f(Object o) {
+  // See: https://github.com/dart-lang/linter/issues/2163
+  o as int; // OK
+  return null;
+}
+
+notReturned() {
+  1; // LINT
+  1 + 1; // LINT
+  foo; // LINT
+  new MyClass().foo; // LINT
+  new MyClass()..foo; // LINT
+  new MyClass()
+    ..getter // OK
+    ..foo() // OK
+    ..foo; // LINT
+  []; // LINT
+  <dynamic, dynamic>{}; // LINT
+  "blah"; // LINT
+  ~1; // LINT
+
+  getter; // OK
+  field; // LINT
+  new MyClass().getter; // OK
+  new MyClass().field; // LINT
+  var myClass = new MyClass();
+  myClass; // LINT
+  myClass.getter; // OK
+  myClass.field; // LINT
+
+  new MyClass(); // OK
+  foo(); // OK
+  new MyClass().foo(); // OK
+  var x = 2; // OK
+  x++; // OK
+  x--; // OK
+  ++x; // OK
+  --x; // OK
+  try {
+    throw new Exception(); // OK
+  } catch (x) {
+    rethrow; // OK
+  }
+}
+
+asConditionAndReturnOk() {
+  if (true == someBool) // OK
+  {
+    return 1 + 1; // OK
+  } else if (false == someBool) {
+    return foo; // OK
+  }
+  while (new MyClass() != null) // OK
+  {
+    return new MyClass().foo; // OK
+  }
+  while (null == someBool) // OK
+  {
+    return new MyClass()..foo; // LINT
+  }
+  for (; someBool ?? someBool;) // OK
+  {
+    return <dynamic, dynamic>{}; // OK
+  }
+  do {} while ("blah".isEmpty); // OK
+  for (var i in []) {} // OK
+  switch (~1) // OK
+      {
+  }
+
+  () => new MyClass().foo; // LINT
+  myfun() => new MyClass().foo; // OK
+  myfun2() => new MyClass()..foo; // LINT
+}
+
+myfun() => new MyClass().foo; // OK
+myfun2() => new MyClass()..foo; // LINT
+
+expressionBranching() {
+  null ?? 1 + 1; // LINT
+  null ?? foo; // LINT
+  null ?? new MyClass().foo; // LINT
+  false || 1 + 1 == 2; // LINT
+  false || foo == true; // LINT
+  false || new MyClass() as bool; // OK
+  false || new MyClass().foo == true; // LINT
+  true && 1 + 1 == 2; // LINT
+  true && foo == true; // LINT
+  true && new MyClass() as bool; // OK
+  true && new MyClass().foo == true; // LINT
+
+  // ternaries can detect either/both sides
+  someBool // OK
+      ? 1 + 1 // LINT
+      : foo(); // OK
+  someBool // OK
+      ? foo() // OK
+      : foo; // LINT
+  someBool // OK
+      ? new MyClass() // OK
+      : foo(); // OK
+  someBool // OK
+      ? foo() // OK
+      : new MyClass().foo; // LINT
+  someBool // OK
+      ? [] //LINT
+      : {}; // LINT
+
+  // not unnecessary condition, but unnecessary branching
+  foo() ?? 1 + 1; // LINT
+  foo() || new MyClass() as bool; // OK
+  foo() && foo == true; // LINT
+  foo() ? 1 + 1 : foo(); // LINT
+  foo() ? foo() : foo; // LINT
+  foo() ? foo() : new MyClass().foo; // LINT
+
+  null ?? new MyClass(); // OK
+  null ?? foo(); // OK
+  null ?? new MyClass().foo(); // OK
+  false || foo(); // OK
+  false || new MyClass().foo(); // OK
+  true && foo(); // OK
+  true && new MyClass().foo(); // OK
+  someBool ? foo() : new MyClass().foo(); // OK
+  foo() ? foo() : new MyClass().foo(); // OK
+  foo() ? new MyClass() : foo(); // OK
+}
+
+inOtherStatements() {
+  if (foo()) {
+    1; // LINT
+  }
+  while (someBool) {
+    1 + 1; // LINT
+  }
+  for (foo; foo();) {} // LINT
+  for (; foo(); 1 + 1) {} // LINT
+  for (;
+      foo();
+      foo(), // OK
+      1 + 1, // LINT
+      new MyClass().foo) {} // LINT
+  do {
+    new MyClass().foo; // LINT
+  } while (foo());
+
+  switch (foo()) {
+    case true:
+      []; // LINT
+      break; // OK
+    case false:
+      <dynamic, dynamic>{}; // LINT
+      break; // OK
+    default:
+      "blah"; // LINT
+  }
+
+  for (var i in [1, 2, 3]) {
+    ~1; // LINT
+  }
+}
+
+bool someBool = true;
+bool foo() => true;
+get getter => true;
+int field;
+
+class MyClass {
+  int field = 0;
+  bool foo() => true;
+
+  get getter => true;
+
+  MyClass();
+  MyClass.named();
+}